Update platform classes to use OVERRIDE / FINAL when needed

Source/platform/graphics/ImageDecodingStore.h

Index: Source/platform/graphics/ImageDecodingStore.h
diff --git a/Source/platform/graphics/ImageDecodingStore.h b/Source/platform/graphics/ImageDecodingStore.h
index 07b16728ad1f4acc7e8597d0379f0a40ecbfc80f..2febdcca9596c7d7f9945cf77ba21fe422f7857b 100644
--- a/Source/platform/graphics/ImageDecodingStore.h
+++ b/Source/platform/graphics/ImageDecodingStore.h
@@ -197,7 +197,7 @@ private:
         CacheEntry* m_next;
     };
 
-    class ImageCacheEntry : public CacheEntry {
+    class ImageCacheEntry FINAL : public CacheEntry {
     public:
         static PassOwnPtr<ImageCacheEntry> createAndUse(const ImageFrameGenerator* generator, PassOwnPtr<ScaledImageFragment> image)
         {
@@ -212,8 +212,8 @@ private:
 
         // FIXME: getSafeSize() returns size in bytes truncated to a 32-bits integer.
         //        Find a way to get the size in 64-bits.
-        virtual size_t memoryUsageInBytes() const { return cachedImage()->bitmap().getSafeSize(); }
-        virtual CacheType type() const { return TypeImage; }
+        virtual size_t memoryUsageInBytes() const OVERRIDE { return cachedImage()->bitmap().getSafeSize(); }
+        virtual CacheType type() const OVERRIDE { return TypeImage; }
 
         static ImageCacheKey makeCacheKey(const ImageFrameGenerator* generator, const SkISize& size, size_t index, size_t generation)
         {
@@ -227,7 +227,7 @@ private:
         OwnPtr<ScaledImageFragment> m_cachedImage;
     };
 
-    class DecoderCacheEntry : public CacheEntry {
+    class DecoderCacheEntry FINAL : public CacheEntry {
     public:
         static PassOwnPtr<DecoderCacheEntry> create(const ImageFrameGenerator* generator, PassOwnPtr<ImageDecoder> decoder, bool isDiscardable)
         {
@@ -241,8 +241,8 @@ private:
         {
         }
 
-        virtual size_t memoryUsageInBytes() const { return m_size.width() * m_size.height() * 4; }
-        virtual CacheType type() const { return TypeDecoder; }
+        virtual size_t memoryUsageInBytes() const OVERRIDE { return m_size.width() * m_size.height() * 4; }
+        virtual CacheType type() const OVERRIDE { return TypeDecoder; }
 
         static DecoderCacheKey makeCacheKey(const ImageFrameGenerator* generator, const SkISize& size)
         {